The present inventions are related to systems and methods for accessing data from a storage medium, and more particularly to systems and methods for determining target coefficients for retrieving data from a storage medium.
A typical storage device includes a magnetic storage medium that includes information that is magnetically represented on the storage medium. A head is disposed in relation to the storage medium that senses the magnetically represented information and provides an electrical signal representing the information. This electrical signal is ultimately passed to a data detection circuit that performs one or more data detection processes in order to recover the information originally written to the storage medium. There is generally some variability in the head/medium combinations that are used. Thus, in the manufacturing process, each storage device is tested with a variety of channel settings to determine which settings work best for the particular head/medium combination.
An example of calibrating channel settings is shown in FIG. 1. Turning to FIG. 1, a flow diagram 100 depicts a prior art approach for selecting channel settings during a manufacturing process. Following flow diagram 100, a search mode is selected (block 105). The search mode utilizes a list of previously identified likely target settings. An initial set of target settings from the list of likely target settings are selected (block 110). Selecting the target settings includes identifying a previously untested set of target settings from the list, and applying the target settings to the read circuitry of the storage device. At this point, data is passed to the read circuitry and a data decode/detection is performed on the received data stream (block 115). An error rate for the process is determined (block 120), and the determined error rate is stored in relation to the selected target settings (block 125).
It is then determined if there is another set of target settings on the list of channel settings that remains to be tested (block 130). Where another set of target settings remains to be tested (block 130), the next set of target settings from the list of likely target settings is selected (block 135), and the processes of blocks 115-130 are repeated for this set of target settings. Alternatively, where all of the target settings from the list of target settings have been tested (block 130), the set of target settings that provided the best error rate (i.e., minimum errors) is selected (block 140). This optimal set of target settings is applied to the read circuitry (block 145) and a normal mode of operation is selected (block 150).
It is common for the search approach of flow diagram 100 to involve hundreds of target settings, and to be used to test multiple heads and/or disk zones. For each of the target settings, calibration for CTF cutoff/boost, FIR filters and/or media noise parameters may be performed. As testing one set of target settings can require several minutes, the process of flow diagram 100 involving the testing of hundreds or even thousands of target settings can require a substantial amount of time. Such use of time is costly to a company manufacturing storage devices.
Hence, for at least the aforementioned reasons, there exists a need in the art for advanced systems and methods for selecting channel settings.